1. Field of the Invention
The invention relates to an antieject device for rod-like control members of nuclear reactors being passed through a pressure-tight duct or encapsulation of a wall of the nuclear reactor pressure vessel communicating with the pressure vessel plenum, the control members having first and second control member segments, a lower or inner absorber part of the second control member segment being partly or fully insertable into or retractable out of the reactor core for controlling reactivity, and an outer drive part of the first control member segment bringing the control member into interaction with a control drive for adjusting the control member along the longitudinal direction thereof, wherein differential pressure forces engaging the control member and seeking to force the control member out of the pressure vessel and thereby accelerating the control member upon the accidental occurrence of a leak at the encapsulation, are restrained from ejection at the first control member segment.
2. Description of Related Art
Such an antieject device is known from German Published, Prosecuted Application DE-AS 19 11 057. However, that document does not show the core structure of the nuclear reactor in detail. An overview of a nuclear reactor pressure vessel with its core structure and the control members and drive mechanisms therefor can be found in the publication entitled "Druckwasserreaktoren" [Pressurized Water Reactors], Catalog No. KWU 228, Code No. 10 613 Ws. 11 733, especially pages 4 and 8.
In the known antieject device described in the aforementioned German Published, Prosecuted Application DE-AS 19 11 057, a spring-biased annular piston is disposed in an annular space on an end facing toward the pressure vessel being formed by the control member drive rod and the thimble or encapsulation. That annular piston is connected to latches and, due to a pressure difference between the interior of the pressure vessel and the thimble, guide surfaces disposed in the thimble convert an axial motion of the annular piston into a radial motion of the latches until they engage teeth disposed on the outer periphery of the drive rod In the case of leakage at the thimble or encapsulation, the known antieject device offers adequate protection. However, in the hypothetical event of failure due to separation of the thimble, the annular tube can be torn away as well, in which case there is no adequate security against the second control member segment and its absorber part being driven out of the core.
It is accordingly an object of the invention to provide an antieject device for control members of nuclear reactors, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and to do so in such a way that it is assured that the second control member segment and its absorber part will remain in the reactor core and if it has not yet assumed the fully inserted position it will be able to drop into that position, not only if there is a leak at the encapsulation surrounding the outer part of the control member or at a corresponding thimble but also in the event of a rupture of the thimble.